Automotive technologies continually strive to make vehicles safer. In one aspect of vehicle safety, it is known to provide a vehicle with means to detect potential collisions and to take appropriate actions to avoid the same. For example, vehicles have been equipped with numerous types of sensors (e.g., infra-red sensors) which are able to broadcast radiation towards a potential obstacle (a tree, building, or another vehicle for example), receive radiation reflected from that obstacle, and determine that obstacle's distance and hence its potential as a collision hazard.
A developing technology in this area comprises antenna structures operating at or near 77 GHz frequencies. Such antenna structures include the ability to transmit and detect reflected 77 GHz radiation, and thus may be referred to as transceivers. A simple illustration of such a transceiver 12 mounted in a vehicle 10 is illustrated in FIG. 1. The transceiver 12 may be mounted anywhere in the vehicle 10 so long as the transmission and detection of the radiation is not significantly impeded, and preferably may be mounted inside the bumper of the vehicle. In the specific example illustrated, the transceiver 12 is positioned in the front bumper of the vehicle allowing for assessment of potential hazards in front of the vehicle. As the broadcast radiation is preferably generally beam shaped, it is usually beneficial to cause the radiative beam to oscillate from left to right in front of the vehicle so as to “sweep” an arc-shaped sector in front of the vehicle. Using 77 GHz transceivers, the beam is usually swept between +/−10 degrees (θ) at a frequency of about 10 Hz or so, and has an effective distance for assessing potential hazards of approximately 100 meters. When such a transceiver 12 is incorporated into a vehicle 10, potential collision hazards can be detected, which is useful in its own right as a safety feature, and is further useful in other respects, for example, as input to an adaptive cruise control system which automatically slows the car when hazards are detected at a certain distance.
FIGS. 2A and 2B show the basic components of a typical transceiver 12 in further detail, including a parabolic reflector dish 16, a horn antenna 18, relevant electronics as exemplified by a printed circuit board (PCB) 22, and a substrate structure or housing 14 for mounting and/or housing the same. The PCB 22 generates and transmits the radiation 20 from the horn antenna 18, and similarly receives reflected radiation from a potential collision hazard as noted above. The horn antenna 18 is located at a focal point of the parabolic reflective surface 16a of the dish 16 such that radiation 20 broadcast from the horn antenna leaves the dish 16 in a generally horizontal beam, and similarly so that reflected radiation 20 is eventually focused back to the horn antenna 18 and the PCB 22 for detection. (The dish 16 as shown generally represents the “upper half” of a parabola). Other antenna configurations have been used with vehicular radar sensors, but using a parabolic antenna is generally preferred for producing a narrow beam for multiple object detection.
As noted earlier, the beam is swept (i.e., through angle θ) in any number of well known ways, for example, by causing the parabolic dish 16 to oscillate back and forth. Because such oscillation schemes are well known and not particularly important in the context of the invention, such details are not shown. However, it suffices to say that the dish 16 can be made to oscillate with respect to the housing 14 by mounting it thereto with springs or dampers to allow the dish to swivel, and by cyclically powering solenoids within the housing 14 to swivel the dish 16 by electromagnetic force.
Further details concerning the foregoing concepts and transceiver structures and controls can be found in U.S. Pat. Nos. 6,542,111; 6,646,620; 6,563,456; and 6,480,160, which are incorporated herein by reference in their entireties.
A major drawback to the collision detection transceiver 12 of the type illustrated is its cost, particularly as it related to the horn antenna 18. As a three-dimensional waveguide, the horn antenna is generally rather complex to design and manufacture, as the angles, lengths and the other various dimensions of the waveguide must be specifically tailored to give optimum performance for the radiation 20 (i.e., at 77 GHz) in question. This accordingly adds significant cost to the transceiver 12, which generally hampers use of the transceiver in vehicles that generally cannot be labored with substantial add-on costs. Moreover, from a functional standpoint, the use of the horn antenna adds additional structural complexity to the overall design of the transceiver assembly, as it essentially “sticks out” of the assembly, must be precisely coupled to the PCB 22, is susceptible to damage and misalignment, etc.
In short, room exists to improve upon existing vehicular collision detection transceivers, and this disclosure presents solutions.